1. 6.2 Wave Phenomena

2. Wave Interference
As the waves move outward from their respective sources, they pass through one another.

3. Wave Interference
As they pass through one another, the waves interact to form an interference pattern of light and dark bands.

4. Constructive Interference
When two waves arrives simultaneously at the same place
and they are IN phase…
IN PHASE = a crest from A arrives simultaneously with a crest from B
The amplitudes of the waves are ADDITIVE
The resultant waves has twice the amplitude of the individual waves from A and B

5. Destructive Interference
When two waves arrives simultaneously at the same place
and they are OUT of phase…
OUT OF PHASE = a crest from A arrives simultaneously with a trough from B
The two waves CANCEL each other

6. Wave Interference
Occurs with all sorts of waves and you can see, hear the effect of this in everyday life

7. Observing Interference
Hold one end of the spring, and have a partner hold the opposite end.
One of you will generate a transverse pulse, and observe its motion along the spring.
After the pulse has dissipated, the other member of the team will generate an identical pulse.
What will happen when you and your partner generate pulses simultaneously?
Try it!!
What did you observe? Did you see the expected result?

8. Observing Interference
Repeat the previous procedure, BUT now create two waves with the opposite displacements
What will happen when you and your partner generate opposite pulses simultaneously?
Try it!!
What did you observe? Did you get the expected result?

9. Thomas Young’s Double Slit Experiment
Showed that light is a wave!!

10. Thomas Young’s Double Slit Experiment

11. Thomas Young’s Double Slit Experiment
Created a series of bright (constructive interference) and dark (destructive interference) bands
At C, D, and E, the crests arrived simultaneously and troughs arrived simultaneously
At dark bands (called NODAL LINES), the crests and troughs arrived at the same time = cancel each other = no light produced

12. The experiment allows calculating WAVELENGHT
The difference between AC and BC is BF = λ
Using trigonometry you can find out that

13. Diffraction
When a wave spreads out as it passes through a narrow opening, around corners or small obstacles

14. How can we account for this change in pitch?
If you stand on the street while an ambulance speeds by with its siren on, you will notice the pitch of the siren change.
The pitch will be higher as the ambulance approaches and will be lower as it moves away.
How can we account for this change in pitch?

15. The Doppler Effect = The Frequency Shift
This was explained by a guy named C.J. Doppler

16. The Doppler Effect = The Frequency Shift
If an ambulance is parked,
an observer and a driver of the ambulance hear the same pitch (frequency)

17. The Doppler Effect = The Frequency Shift
If an ambulance is moving,
the wave fronts reach an observer
in front of the ambulance
(Observer A) more often than they
would if the ambulance were
stationary =
frequency heard by Observer A is
greater than the source frequency

18. The Doppler Effect = The Frequency Shift
If an ambulance is moving,
the wave fronts reach an observer
behind the ambulance
(Observer C) less often than they
would if the ambulance were
stationary =
the frequency heard by Observer C
is less than the source frequency

19. The Sound Barrier, Shock waves and Sonic Boom
Read on your own, it will not be on a test

20. 6.2 Review Questions (all except 7, 9, 10)

21. Chapter 6 Review Questions (all except 14,15)